G, P, C, and M

From The p Factor: One General Psychopathology Factor in the Structure of Psychiatric Disorders? by Avshalom Caspi et al.  Fro the Abstract:

Mental disorders traditionally have been viewed as distinct, episodic, and categorical conditions. This view has been challenged by evidence that many disorders are sequentially comorbid, recurrent/chronic, and exist on a continuum. Using the Dunedin Multidisciplinary Health and Development Study, we examined the structure of psychopathology, taking into account dimensionality, persistence, co-occurrence, and sequential comorbidity of mental disorders across 20 years, from adolescence to midlife. Psychiatric disorders were initially explained by three higher-order factors (Internalizing, Externalizing, and Thought Disorder) but explained even better with one General Psychopathology dimension. We have called this dimension the p factor because it conceptually parallels a familiar dimension in psychological science: the g factor of general intelligence. Higher p scores are associated with more life impairment, greater familiality, worse developmental histories, and more compromised early-life brain function. The p factor explains why it is challenging to find causes, consequences, biomarkers, and treatments with specificity to individual mental disorders. Transdiagnostic approaches may improve research.

From The p Factor by Arnold Kling.  The suheading is An under-studied hypothesis about mental disorders.  

In 2014, Avshalom Caspi and others published a paper arguing that the correlations among psychological disorders suggest the existence of a common factor. They proposed calling this the p factor. It is analogous to the g factor, known as general intelligence, popularly known as IQ.

I am surprised to find very little in the way of follow-up literature. When a striking and controversial theory appears in economics (take the Efficient Market Hypothesis, for example), the follow-on literature, pro and con, is voluminous.

I have not taken so much as one course in personality psychology. But the p-factor theory strikes me as interesting, in the same way that the EMH is interesting.

For one thing, the p-factor theory puts a focus on innate factors in determining mental health. But it suggests that parents with one disorder might have children with very different disorders.

Someone with a high p factor is likely to have parents with high p factors and/or experienced brain development that resulted in a high p factor. See Kevin Mitchell’s Innate.

For example, when I see an essay that refers to an old paper on mothers of boys with gender identity disorder showing that the mothers have dramatically higher incidence of borderline personality, I do not presume that the mothers’ behavior toward their sons caused their sexual identity issues. Instead, I think of the mothers as having a high p factor, which they pass along to their sons, and this happens to manifest itself in such issues.

When Jonathan Haidt wants to blame an increase in teen depression on an environmental factor (smart phones and social media), how does this relate to the p factor? One possibility is that the p factor predicts a propensity for mental disorders, but the environment heavily influences which mental disorders become manifest. Smart phones and social media do not affect the p factor, but they trigger an epidemic of teen depression, because that is how a high p factor manifests itself in the current environment. Before smart phones, the same people would have been susceptible to mental illness, but it might have manifested differently or not at all.

Later on he further speculates:

Another possibility that occurs to me is that instead of (or in addition to) thinking in terms of a p factor that causes mental illness we might think of a factor that protects against mental illness making someone dysfunctional. This might be termed a “coping factor,” which we could call c. That is, if you have two people with a propensity for a given disorder, the one with higher c will be able to overcome the disorder, and the one with lower c will be unable to do so. So we have the high-functioning autistic compared to the low-functioning autistic. We have the creative and original thinker compared to the schizophrenic.

To this hypothesized world of g, p, and c, one might add an additional measure of m for morbidity.  What is the individual's overall physical capacity in terms of strength and health?  

The ideal balance is something like High G (processing capability), Low P (not prone to mental illnesses), and High C (significant coping capability), all complemented by High M (overall healthiness).  

It all makes sense.  Perhaps further research might be forthcoming.